Electronic Gaming Machine and Gaming Method

ABSTRACT

An electronic gaming machine has an electronic game controller and a display where game symbols are arranged in an array, where R is the number of available predetermined game positions in the array. The electronic game controller determines the appearance of a group of special symbols in the predetermined game positions, the group affecting the outcome of the game, and the probability of the group appearing on the array is less than 1 in X, X being the average number of games played with R predetermined game positions. A gaming method is also provided.

BACKGROUND

The present invention relates to an electronic gaming machine and agaming method for an electronic gaming machine, where the electronicgaming machine also includes devices that permit gaming online on theInternet or download and execute computer software to enable gaming onthat device. The invention has been developed primarily for use as anelectronic gaming machine and will be described hereinafter by referenceto this application.

The following discussion of the prior art is intended to present theinvention in an appropriate technical context and allow its advantagesto be properly appreciated. Unless clearly indicated to the contrary,however, reference to any prior art in this specification should not beconstrued as an express or implied admission that such art is widelyknown or forms part of common general knowledge in the field.

Conventional gaming machines typically involve awarding prizes to aplayer according to predetermined combinations of game symbols thatappear on an array of game squares displayed on a screen, typicallyorganised into three rows and five columns (a 5×3 array). Other arrays,such as a 3×3 or 4×3, may be used. Each gaming machine randomly selectsthe game symbols that appear on the array, each column of the arraybeing a “reel”.

In an electronic gaming machine, the mechanical reels are replaced withvideo images of the reels, which are displayed on a video displayscreen. The electronic gaming machine has an internal electronic gamecontroller, typically a computer, that controls the display of images onthe video display screen so that the reels are visibly spun on thescreen to simulate a physical reel of a traditional gaming machine.Electronic gaming machines are also more versatile in presenting gameinformation, varying the probabilities for a player to win a prize andvarying the type of game that is played.

In an electronic gaming machine, the mechanical reels are replaced withvideo images of the reels, which are displayed on a video displayscreen. The electronic gaming machine has an internal electronic gamecontroller, typically a computer, that controls the display of images onthe video display screen so that the reels are visibly spun on thescreen to simulate a physical reel of a traditional gaming machine.Electronic gaming machines are also more versatile in presenting gameinformation, varying the probabilities for a player to win a prize andvarying the type of game that is played. Conventionally, such reel-typegames comprise a main or base game offered by the electronic gamingmachine.

Bonus or “feature” games may be provided by an electronic gaming machinein addition to the base or main game. Typically feature games use thesame set of reels as the main game and are limited to a set of freegames operated under a single set of rules that may be slightly modifiedfrom the base game. Once the free feature games have been played, theelectronic gaming machine resets itself and returns the player back tothe base game.

There is always a possibility of the same symbol appearing in eachposition on each reel or a majority of reels. However, the probabilityof such an event (also called the “hit rate”) occurring is very low suchthat it is very rare for such an event to occur even if one were to playthe electronic gaming machine for long periods of time.

Consequently, it is difficult to retain player interest because there isno apparent incentive for the player to continue playing the sameelectronic gaming machine.

It is an object of the present invention to overcome or substantiallyameliorate one or more of the disadvantages of prior art, or at least toprovide a useful alternative.

It is an object of the invention in at least one preferred form toprovide an electronic gaming machine and a method for controlling anelectronic gaming machine that encourages player interest.

SUMMARY

According to a first aspect of the invention, there is provided anelectronic gaming machine comprising:

a display for displaying a game comprising game symbols arranged into anarray of predetermined game positions, wherein R is the number ofavailable predetermined game positions for play in said game andpredetermined winning combinations of randomly selected game symbols ineach game award prizes to a player, and

an electronic game controller for controlling the display of said gamesymbols on said display,

wherein said electronic game controller determines the appearance of agroup of special symbols in said predetermined game positions, saidgroup affecting the outcome of said game and S being the number ofspecial symbols in said group, and

wherein the probability of said group appearing on said array is lessthan 1 in X, X being the average number of games played with said Rpredetermined game positions.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise”, “comprising”, and thelike are to be construed in an inclusive sense as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to”.

Preferably, said game is a base game and said predetermined gamepositions are selectable for play by said player, wherein X is thetheoretical average number of games required for the appearance saidgroup to occur when R predetermined game positions are selected forplay.

Alternatively or additionally, said game comprises a feature game and atrigger event in a base game activates said feature game for play, saidpredetermined game positions being selectable for play by said player insaid feature game, and wherein X is the theoretical average number ofgames required for the appearance of said group to occur in said featuregame multiplied by the probability of said trigger event occurring insaid base game, when R predetermined game positions are selected forplay.

Preferably, said predetermined game positions are arranged in rowsand/or columns in said array.

Preferably, said special symbols in said group are associated with eachother. More preferably, said special symbols comprise at least one ormore of game symbols that are visually the same, have a common element,share a common enhancing effect on the outcome of the game, and have anadditional function in said game. In one preferred form, said commonelement comprises an image associated with, or a representation of, saidspecial symbols in said group. In another preferred form, said commonelement comprises an image associated with, or a representation of, saidgroup. In a further preferred form, said additional function is to actas at least one of a scatter symbol, trigger symbol, substitute symboland jackpot symbol.

Preferably, at least two special symbols of said group form part of atleast one of said predetermined winning combinations of game symbols.Alternatively, at least two special symbols of said group form part ofat least two of said predetermined winning combinations of game symbols.

Preferably, X is less than or equal to 10,000. More preferably, X isfrom 5,000 to 10,000. Even more preferably, X is from 1,000 to 5,000. Itis further preferred that X is from 750 to 1,000. It is even furtherpreferred that X is from 500 to 750. Yet more preferably, X is from 250to 500. In one preferred form, X≦100. In another preferred form, X≦50.In a further preferred form, X≦25.

Preferably, said predetermined game positions are arranged in columns insaid array and said group comprises at least two special symbols in atleast two different columns.

Preferably, said predetermined game positions are arranged in columns insaid array and said group comprises at least two predetermined gamepositions from two adjacent columns. Alternatively, said predeterminedgame positions are arranged in columns in said array and said groupcomprises at least 80% of the predetermined game positions in twoadjacent columns. In one preferred form, said predetermined gamepositions are arranged in columns in said array and said group comprisesall the predetermined game positions in two adjacent columns.

Preferably, S=R. Alternatively, 6<S<R. In another alternative, 9<S<R. Inyet another alternative, 12<S<R. In a further alternative, S=R−1. In ayet further alternative, S=R−2. In a further alternative, S=R−3. In afurther alternative, R>15 and S>9. In a further alternative, S>0.5×R. Ina further alternative, S>0.6×R. In a further alternative, S>0.7×R. In afurther alternative, S 0.8×R. In a further alternative, S>0.9×R.

Preferably, said group occupies at least ten predetermined gamepositions adjacent each other starting from the rightmost side of saidarray. Alternatively, said group occupies at least ten predeterminedgame positions adjacent each other starting from the rightmost side ofsaid array.

Preferably, said group occupies at least fifteen predetermined gamepositions adjacent each other starting from the rightmost side of saidarray. Alternatively, said group occupies at least fifteen predeterminedgame positions adjacent each other starting from the leftmost side ofsaid array.

Preferably, said group occupies at least the predetermined gamespositions to the left of a centre line of said array. Alternatively,said group occupies at least the predetermined games positions to theright of a centre line of said array.

Preferably, said special symbol comprises at least one of a top payinggame symbol in which a combination of said top paying game symbolsconfers the highest prize value; a substitute symbols, a symbolequivalent to said substitute symbol or any symbol associated with saidsubstitute symbol, and a reveal symbol that changes, transforms ormorphs into any game symbols and at least pays winnings on the resultantsymbols.

Preferably, said electronic game controller randomly determines theappearance of said group. More preferably, the trigger event comprises arandom event determined by said electronic game controller at the startof play of said game.

Preferably, said group appears in response to a trigger event on saidarray. In one preferred form, said trigger event comprises theappearance of one or more trigger symbols on said array. In anotherpreferred form, the trigger event comprises an in-game event during playof said game.

Preferably, said game comprises a plurality of additional arrays of gamesymbols arranged in predetermined game positions and the number ofpredetermined game positions R is limited to the available predeterminedgame positions of said array and excludes the predetermined gamepositions of said additional arrays.

Preferably, said game comprises a sequence of plays of said game andwherein S=R is guaranteed for at least one of said plays that are playedduring said sequence. In one preferred form, said game comprises aplurality of said sequences such that S=R is guaranteed for at least oneof said plays that is played for each of said sequences. In oneparticularly preferred form, said game comprises a base game and afeature game, said feature game being triggered by a trigger event insaid base game and comprising a sequence of plays of said feature game,wherein S=R is guaranteed for at least one of said plays that is playedduring said sequence for each feature game triggered by said triggerevent.

Preferably, said game comprises a sequence of plays of said game andwherein S>0.5×R is guaranteed for at least one of said plays that areplayed during said sequence. In one preferred form, said game comprisesa plurality of said sequences such that S>0.5×R is guaranteed for atleast one of said plays that is played for each of said sequences. Inone particularly preferred form, said game comprises a base game and afeature game, said feature game being triggered by a trigger event insaid base game and comprising a sequence of plays of said feature game,wherein S>0.5×R is guaranteed for at least one of said plays that isplayed during said sequence for each feature game triggered by saidtrigger event.

Preferably, said game comprises a jackpot prize. More preferably, saidjackpot prize comprises a mystery jackpot. In one preferred form, saidgame shares said jackpot prize with another game played on saidelectronic gaming machine. In another preferred form, said game sharessaid jackpot prize with another game played on a different electronicgaming machine to said electronic gaming machine.

Preferably, said electronic game controller is configured to display abase game and/or a feature game on said display. More preferably, saidgame comprises said base game. Alternatively, said game comprises saidfeature game.

Preferably, the game symbols in said feature game and said base game arearranged in arrays of the same shape or type. Alternatively, said gamesymbols in said feature game and said base game are arranged indifferently shaped arrays. The shapes of said arrays are preferablyrectangular, circular, triangular, oval, semi-circular or othernon-rectangular shape.

Preferably, said electronic game controller causes the display of saidfeature game in response to said trigger event. Alternatively, saidelectronic game controller causes the display of said feature game andsaid base game during play of said base game, said feature game beinginactive until triggered. In this preferred form, the change in saidfeature game from being inactive to active may be indicated on thedisplay.

Preferably, the electronic gaming machine comprises a mobile electronicgaming device. More preferably, said mobile electronic gaming devicecomprises a handheld electronic device. Alternatively, said electronicgaming machine comprises a computer. More preferably, said computer isconnected to a communication network.

According to a second aspect of the invention, there is provided agaming method for playing an electronic gaming machine comprising adisplay and an electronic game controller, the method comprising thesteps of:

controllably displaying game symbols on said display for playing a game,wherein said game symbols are arranged into an array of predeterminedgame positions, wherein R is the number of available predetermined gamepositions for play in said game and predetermined winning combinationsof randomly selected game symbols award prizes to a player;

controllably determining the appearance of a group of special symbols onsaid display, S being the number of special symbols in said group, sothat the probability of said group appearing on said array is less than1 in X, X being the average number of games played with said Rpredetermined game positions, and

determining any changes to the outcome of said game based on theappearance of said group.

Preferably, said game is a base game and said method further comprisesthe step of selecting predetermined game positions for play, wherein Xis the theoretical average number of games required for the appearancesaid group to occur when R predetermined game positions are selected forplay.

Alternatively or additionally, said game comprises a feature game andsaid method further comprises the steps of activating said feature gamein response to a trigger event in a base game and selecting saidpredetermined game positions for play in said feature game, wherein X isthe theoretical average number of games required for the appearance ofsaid group to occur in said feature game multiplied by the probabilityof said trigger event occurring in said base game, when R predeterminedgame positions are selected for play.

Preferably, said method further comprises arranging said predeterminedgame positions in rows and/or columns in said array.

Preferably, said method further comprises associating said specialsymbols in said group with each other. More preferably, said associatingstep comprises providing said special symbols that comprise at least oneor more of game symbols that are visually the same, have a commonelement, share a common enhancing effect on the outcome of the game, andhave an additional function in said game. In one preferred form, saidassociating step comprises associating an image associated with, orproviding a representation of, said special symbols in said group. Inanother preferred form, said associating step comprises associating animage associated with, or providing a representation of, said group. Ina further preferred form, said associating step comprises providing saidadditional function that acts as at least one of a scatter symbol,trigger symbol, substitute symbol and jackpot symbol.

Preferably, said group determining step comprises causing at least twospecial symbols of said group to form part of at least one of saidpredetermined winning combinations of game symbols. Alternatively, saidgroup determining step comprises causing at least two special symbols ofsaid group to form part of at least two of said predetermined winningcombinations of game symbols.

Preferably, said method further comprises making X≦10,000. Morepreferably, said method further comprises making X is from 5,000 to10,000. Even more preferably, said method further comprises making X isfrom 1,000 to 5,000. It is further preferred that said method furthercomprises making X is from 750 to 5,000. It is even further preferredthat said method further comprises making X is from 500 to 750. Yet morepreferably, said method further comprises making X is from 250 to 500.In one preferred form, said method further comprises making X≦100. Inanother preferred form, said method further comprises making X≦50. In afurther preferred form, said method further comprises making X≦25.

Preferably, said method further comprises arranging said predeterminedgame positions in columns in said array, and said group determining stepcomprises causing at least two special symbols to appear in at least twodifferent columns.

Preferably, said method further comprises arranging said predeterminedgame positions in columns in said array, and said group determining stepcomprises causing two special symbols to appear in at least twopredetermined game positions from two adjacent columns. Alternatively,said method further comprises arranging said predetermined gamepositions in columns in said array, and said group determining stepcomprises causing special symbols to appear in at least 80% of thepredetermined game positions in two adjacent columns. In one preferredform, said method further comprises arranging said predetermined gamepositions in columns in said array, and said group determining stepcomprises causing special symbols to appear in all the predeterminedgame positions in two adjacent columns.

Preferably, said group determining step comprises causing the appearanceof said group such that S=R. Alternatively, said group determining stepcomprises causing the appearance of said group such that 6<S<R. In afurther alternative, said group determining step comprises causing theappearance of said group such that 9<S<R. In yet another alternative,said group determining step comprises causing the appearance of saidgroup such that 12<S<R. In another alternative, said group determiningstep comprises causing the appearance of said group such that S=R−1. Ina further alternative, said group determining step comprises causing theappearance of said group such that S=R−2. In a further alternative, saidgroup determining step comprises causing the appearance of said groupsuch that S=R−3. In a further alternative, said group determining stepcomprises causing the appearance of said group such that R>15 and S>9.In a further alternative, said group determining step comprises causingthe appearance of said group such that S>0.5×R. In a furtheralternative, said group determining step comprises causing theappearance of said group such that S≧0.6×R. In a further alternative,said group determining step comprises causing the appearance of saidgroup such that S≧0.7×R. In a further alternative, said groupdetermining step comprises causing the appearance of said group suchthat S≧0.8×R. In a further alternative, said group determining stepcomprises causing the appearance of said group such that S≧0.9×R.

Preferably, said group determining step further comprises causingspecial symbols to appear in at least ten predetermined game positionsadjacent each other starting from the rightmost side of said array.Alternatively, said group determining step further comprises causingspecial symbols to appear in at least ten predetermined game positionsadjacent each other starting from the rightmost side of said array.

Preferably, said group determining step further comprises causingspecial symbols to appear in at least fifteen predetermined gamepositions adjacent each other starting from the rightmost side of saidarray. Alternatively, said group determining step further comprisescausing special symbols to appear in at least fifteen predetermined gamepositions adjacent each other starting from the leftmost side of saidarray.

Preferably, said group determining step further comprises causingspecial symbols to appear in at least the predetermined games positionsto the left of a centre line of said array.

Preferably, said group determining step further comprises causingspecial symbols to appear in at least the predetermined games positionsto the right of a centre line of said array.

Preferably, said method further comprises providing a plurality ofadditional arrays of game symbols arranged in predetermined gamepositions on said display and restricting R to the availablepredetermined game positions of said array and excluding thepredetermined game positions of said additional arrays.

Preferably, said method further comprises providing a sequence of playsof said game and guaranteeing S=R for at least one of said plays thatare played during said sequence. In one preferred form, said sequenceproviding step comprises providing a plurality of said sequences andsaid guaranteeing step comprises guaranteeing S=R for at least one ofsaid plays that is played for each of said sequences. In oneparticularly preferred form, said game comprises a base game and afeature game, said method further comprising triggering said featuregame in response to a trigger event in said base game, providing asequence of plays of said feature game and guaranteeing S=R for at leastone of said plays that is played during said sequence for each featuregame triggered by said trigger event.

Preferably, said method further comprises providing a sequence of playsof said game and guaranteeing S>0.5×R for at least one of said playsthat are played during said sequence. In one preferred form, saidsequence providing step comprises providing a plurality of saidsequences and said guaranteeing step comprises guaranteeing S>0.5×R forat least one of said plays that is played for each of said sequences. Inone particularly preferred form, said game comprises a base game and afeature game, said method further comprising triggering said featuregame in response to a trigger event in said base game, providing asequence of plays of said feature game and guaranteeing S>0.5×R for atleast one of said plays that is played during said sequence for eachfeature game triggered by said trigger event.

The method also preferably has the preferred features of the firstaspect of the invention stated above, where applicable.

According to a third aspect of the invention, there is provided acomputer system comprising a central processing unit configured forcommunication with an electronic gaming machine, wherein said computersystem is configured to perform the method of the second aspect of theinvention.

According to a fourth aspect of the invention, there is provided acomputer program configured to perform the method of the second aspectof the invention.

According to a fifth aspect of the invention, there is provided anon-transitive carrier medium carrying computer executable code that,when executed on a central processing unit configured for communicationwith an electronic gaming machine, causes the central processing unit toperform the method of the second aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described, by way ofexample only, with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of an electronic gaming machine accordingto an embodiment of the invention;

FIG. 2 is a schematic drawing of an electronic game controller for theelectronic gaming machine of FIG. 1;

FIG. 3 is a schematic drawing illustrating a game displayed on an arrayof the electronic gaming machine of FIG. 1;

FIG. 4 is a schematic drawing illustrating a change to the game of FIG.3;

FIG. 5 is a schematic drawing illustrating a game displayed on an arrayof the electronic gaming machine according to another embodiment of theinvention;

FIG. 6 is a schematic drawing illustrating a game displayed on an arrayof the electronic gaming machine according to yet another embodiment ofthe invention;

FIG. 7 is a schematic drawing illustrating a game displayed on an arrayof the electronic gaming machine according to a further embodiment ofthe invention;

FIG. 8 is a schematic drawing illustrating a game displayed on an arrayof the electronic gaming machine according to a still further embodimentof the invention;

FIG. 9 is a schematic drawing illustrating a game displayed on an arrayof the electronic gaming machine according to another embodiment of theinvention;

FIGS. 10 and 11 are schematic drawings illustrating other possiblechanges to the game according to further embodiments of the invention;

FIG. 12 is a schematic drawing illustrating a game displayed on an arrayof the electronic gaming machine according to a further embodiment ofthe invention; and

FIG. 13 is a schematic drawing illustrating a change to the game of FIG.12.

DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS

Referring to FIG. 1, an electronic gaming machine 1 according to a firstembodiment of the invention includes a cabinet 2, a console 3 and aninternal electronic game controller 4. The console 3 has various inputdevices including vending slots 5 for receiving monetary bets and aplurality of buttons 6 for actuation by a player. The electronic gamecontroller 4 is generally in the form of a central processing unit, suchas a computer, and is in electronic communication with a display in theform of a video display screen 7, as well as various input devices onthe console 3, as best shown in FIG. 2. It is also appreciated that aperson skilled in the art would readily understand the location and useof the electronic game controller 4 in the electronic gaming machine 1.

The video screen 7 may also display other standard game information (notshown), including the number of pay lines available, the number ofplayer-selected pay lines, the amount of credits per line, the amount ofplayer credits the amount of the current bet wagered by the player, theamount of wins by the player, a message area, a general menu button anda current denomination button indicating the currently selected base betdenomination.

The electronic game controller 4 is programmed to provide a game 8 onthe electronic gaming machine 1 for play by a player, as best shown inFIG. 1. The game 8 has game symbols 9 arranged into an array 10 in theform of five columns or “reels” 11, as best shown in FIG. 3. While thearray 10 is arranged with five columns or “reels” 11 and an even numberof rows, it will be appreciated by one skilled in the art that otherarrays could be used, such as the industry standard 5×3 or 3×3, 4×3,5×5, 4×4, etc. Also, the array 10 can have an uneven number of rowsand/or columns.

The array 10 of the game 8 defines 15 predetermined game positions inthe form of “squares” or cells 12, in which the game symbols 9 appear.The array 10 is arranged so that a player can select one or morepredetermined “pay lines” 13 defined around the array, which correspondto combinations of the game positions 12. The pay lines 13 correspond tothe lines selected by the player and generally comprise at least onegame position 12 from each reel 11. The number of pay lines 13 that canbe selected by the player depends on the amount of the monetary bet forplaying a game on the array 10. In this embodiment, each of the cells 12is available for play in the game 8.

The game symbols 9 can include a mixture of picture symbols (such asanimal symbols, playing card symbols, scatter symbols, wild card symbolsand trigger symbols to trigger a feature game (if any)). The electronicgame controller 4 randomly determines the appearance of the game symbols9 on the array 10.

The player initially makes a bet using vending slots 5 initiate play ofthe electronic gaming machine 1 to build up credit to play any of theselectable games on the electronic gaming machine. For example, theplayer can bet or wager monetary amounts equivalent to a particularamount of credits, depending on the bet denomination selected for thegame 8. Also, the player can make any additional side bets or ante-betsduring play of the game 8 once the game has commenced to accessadditional features in the game, such as increasing the number ofwinning combinations in the game.

The electronic game controller 4 then causes the reels 11 to appear tovisibly rotate or “spin”, and randomly display the game symbols 9 ineach cell 12. The electronic game controller 4 also randomly determinesthe appearance of a group 15 of two or more special symbols 16 in two ormore of the cells 12, as best shown in FIG. 4. The group 15 affects theoutcome of the game 8 by increasing the chances of obtaining a winningcombination of game symbols 9 and/or the value of the winningcombinations. The special symbols may act as a substitute symbol (i.e.,a wild card), scatter symbol, jackpot symbol or confer a variety of gameenhancing elements, such as free games or a bonus prize.

The electronic game controller 4 controls the probability of the group15 appearing on the array 10 so that it is less than 1 in X, where X isthe average number of games played with the 15 cells 12. Thus, whilethere is some randomness in the appearance of the group 15, it is withinthe predetermined probability parameters. The electronic game controller4 ensures that the probability is kept within the required parameters byadjusting the reel strip or switching to a reel strip having a greaterprobability of the TriggerS symbol 17 appearing where the appearance ofthe group 15 of special symbols 16 has not occurred for a predeterminednumber of plays of the game. By setting this probability, the electronicgame controller 4 controls the frequency of group 15 appearing on thearray 10 and thus adjusts the volatility of the electronic gamingmachine 1.

The average number of games X can be predetermined by the electronicgame controller and is selected so that there is a comparatively greaterlikelihood of the group 15 appearing than typically expected by theplayer on a standard or conventional electronic gaming machine. Forexample, it is preferred that X is at least 10,000, and more preferablyfrom 5,000 to 10,000, even more preferably 1,000 to 5,000. However, inparticularly preferred forms, it is preferred that X is from 750 to1,000, from 500 to 750, from 250 to 500 to ensure that the playerobserves the group 15 1 of special symbols 16 over a period of time. Inother preferred forms, X≦100, X≦50 or X≦25 ensure that the playerobserves the group of special symbols in a single playing session. Byway of contrast, a conventional electronic gaming machine with stackedgame symbols (i.e., the same game symbol on each position so that theyare “stacked” together) on its reel strips typically has about 90 gamesymbols on each reel strip. This means that for an array of the samesize (i.e., fifteen cells 12 in the array 10), the probability of eachof the game symbols appearing in each of the fifteen cells would be 1 in90⁵ (i.e., 1 in 5,904,900,000) for each combination of game symbolsbeing the same that takes up 50% of the array. Similarly, theprobability of more than 50% of the game symbols in the array being thesame would be the as above, multiplied by the number of possiblecombinations of game symbols that would meet the requirement that 50% ofthe game symbols are the same. For example, even if there were 1,000such possible combinations based on the layout of symbols on each reelstrip, the probability would be calculated to be 1 in 5,904,900 games onaverage to trigger the required number of same symbols. In either case,the probability of such an event occurring on a conventional electronicgaming machine is significantly low compared to the probabilities listedabove of the group 15 of special symbols 16 that appear on the array 10,which are at least 1 in 10,000 and as high as 1 in 25.

In this embodiment, the group 15 appears in response to the appearanceof one or more trigger “TriggerS” symbols 17 on the display 7, as bestshown in FIG. 3. Thus, after the reels 11 stop spinning, the electronicgame controller 4 determines whether there are any TriggerS symbols 17on the array 10. If not, then the electronic game controller 4determines whether there are any predetermined winning combinations ofthe game symbols 9 appear in any player-selected pay lines 13, such as“three of a kind”, “four of a kind” and “five of a kind” and/or othercombinations of a “full house”, “straight” or “flush” where the gamesymbols represent playing cards. It will be appreciated that otherwinning combinations of game symbols 9 can also be provided. If so, theelectronic game gaming machine 1 enters a winning game state and awardsa prize according to the displayed predetermined winning combination(s).

Where the TriggerS symbol 17 appears on the array 10, the group 15 ofspecial symbols 16 appear, as best shown in FIG. 4. The group 15comprises all the symbols 9 in the reels 11 a, 11 b and 11 c, includingthe TriggerS symbol 17. The electronic game controller 4 then determineswhether winning combinations of game symbols occur on player-selectedpay lines 13 based on the effect of the special symbols 16. In thisembodiment, the special symbols 16 act as substitute symbols. In thiscase, the electronic game controller 4 has made the group 15 comprise 9special symbols 16, taking up 60% of the available cells 12 in the array10. It is preferable to have at least more than 6 special symbols 16 inthe group 15 as it is sufficiently large to indicate to the player thatthe group has appeared on the array 10.

Thus, by increasing the “hit” rate of the group 15 of special symbols 16to fill several or potentially all of the cells 12 in the array 10, aplayer is more likely to likely to see the array filled or almost filledby the same symbols, thus increasing the chances of a large orsignificant win and retaining the player's interest in playing the sameelectronic gaming machine. Also, it can be seen that the player'sinterest and excitement in the game 8 will be enhanced once the TriggerSsymbol 17 appears as he or she will anticipate the appearance of thegroup 15 of special symbols 16 that is likely to increase the chances ofobtaining a winning combination on the array 10 and/or enhance the valueof any such winning combination.

Another embodiment of the invention is illustrated in FIG. 5, wherecorresponding features have been given the same reference numerals. Inthis embodiment, the appearance of the TriggerS symbol 17 on the array10 as illustrated in FIG. 3 causes the appearance of the group 15 sothat it occupies all four reels 11 a, 11 b, 11 c and 11 d from the lefthand side of the array 10, as best shown in FIG. 5. In addition, wherethe scatter symbol 9 a is part of the group 15, the special symbolbecomes a hybrid special symbol 18 that retains the function of thescatter symbol. This may be done by providing a hybrid version of thespecial symbol 9 b. The hybrid special symbol 18 indicates that itfunctions or acts as both the special symbol 16 and as a scatter symbol9 a. In this case, the hybrid special symbol 18 has the word “scatter”appear with the word “special” to indicate its dual function. However,it will be appreciated that other indicators can be used, includingimages or representations associated with the scatter symbol 9 a toindicate its additional function as a scatter symbol.

A further embodiment of the invention is illustrated in FIG. 6, wherecorresponding features have been given the same reference numerals. Thisembodiment also relies on the appearance of the TriggerS symbol 17 totrigger the appearance of the group 15 of special symbols 16. In thisembodiment, the group 15 is equal to the entire array 10; that is, thespecial symbols 16 fill up all 15 cells 12 in the array 10. This isequivalent to a maximum winning combination for any player-selected payline 13. Also, as a scatter symbol 9 a initially appeared on the array10, its cell 12 has the hybrid special symbol 18 to indicate its dualfunction as a special symbol and as a scatter symbol. Also, there is nohybrid version of the special symbol 16 in the cell 12 that had thesubstitute WILD symbol 9 b as in this embodiment, the special symbols 16act as substitute symbols. If the special symbols 16 have a differentfunction, such as offering a bonus prize, there would be a hybridversion of the special symbol to indicate its dual function as both abonus prize and as a substitute symbol.

Yet another embodiment of the invention is illustrated in FIG. 7, wherecorresponding features have been given the same reference numerals. Inthis embodiment, unlike the others, there is no TriggerS symbol 17 toactivate the appearance of the group 15 of special symbols 16 on thearray 10. Instead, the electronic game controller randomly determineswhether the group 15 should appear on the array 10 and, if so, thenumber of special symbols 16 in the group and where the special symbols16 are located on the array. In this instance, the electronic gamecontroller 4 has the group 15 appear in reels 11 a, 11 b, 11 d and 11 e,omitting central reel 11 c, effectively 80% of the available cells 12 inthe array 10. Also, the substitute symbol 9 b effectively becomes aspecial symbol due to its substitute function, meaning that there arespecial symbols 16 that take up all but two of the available cells 12 inthe array 10.

Another embodiment of the invention is illustrated in FIG. 8, wherecorresponding features have been given the same reference numerals. Thisembodiment is similar to the embodiment of FIG. 7 in that there is noTriggerS symbol 17 to activate the appearance of the group 15 of specialsymbols 16 on the array 10. Instead, the electronic game controllerrandomly determines whether the group 15 should appear on the array 10as described above. In this case, the group 15 comprises all but two ofthe available cells 12 in the array 10. However, the substitute symbol 9b effectively becomes a special symbol due to its substitute function,so that there are special symbols 16 in all but one of the availablecells 12 in the array 10.

Another embodiment of the invention is illustrated in FIGS. 9 to 11,where corresponding features have been given the same referencenumerals. In this embodiment a TriggerSP symbol 20 appears in the array10, as best shown in FIG. 9. The TriggerSP symbol 20 triggers theappearance of both the group 15 of special symbols 16 in at least reels11 a and 11 c, and substitute symbols 9 b in at least reels 11 b and 11d. See FIG. 10. The function of the TriggerSP symbol 20 would beexplained in the game rules, including the identifying the reels 11 inwhich the special symbols 16 and the substitute symbols 9 b appear onthe array 10. The group 15 fills in twelve of the fifteen availablecells 12 in the array, with six of the special symbols 16 being in reels11 a and 11 c. As the substitute symbols 9 b act as a wild card, theyalso act as special symbols and are counted as such by the electronicgame controller 4. Also, as a scatter symbol 9 a initially appeared inreel 11 d, it becomes a hybrid special symbol 25 that acts as asubstitute symbol and a scatter symbol, as well as a special symbol,thus having triple functionality. Thus, the special symbols 16 in thearray 10 are connected or associated by a common element (being theirshared function as a special symbol) even if they are each not the exactsame game symbol.

FIG. 11 illustrates another possible group 15 that may appear as aresult of the TriggerSP symbol 20 appearing in the array of FIG. 9. Inthis case, all the cells 12 available in the array 10 are selected toshow the group 15 of special symbols 16. The group 15 comprises each ofthe cells 12 from reels 11 a, 11 c and 11 e, displayed as specialsymbols 16, the cells 12 from reels 11 b and 11 d displaying substitutesymbols 9 b that act as special symbols and one cell 12 from the reel 11d where the hybrid special symbol 25 having triple functionalityappears.

Another embodiment of the invention is illustrated in FIGS. 12 and 13,where corresponding features have been given the same referencenumerals. This embodiment also uses a TriggerSP symbol 20 as describedin relation to FIGS. 9 to 11 above. In this case, the array 10 is anextended array that has eighteen available cells 12, where the reels 11c, 11 d and 11 e have an additional cell compared to the remaining reels11 a and 11 b, as best shown in FIG. 12. Again, the TriggerSP symbol 20has caused the group 15 of special symbols 16 to be located in each ofthe cells 12 of reels 11 a, 11 c and 11 e, while substitute symbols 9 aappear in the cells of reels 11 b and 11 d also act as special symbols.See FIG. 13. This means that the special symbols fill the entire array10, as in FIG. 11. Similarly, the group 15 also includes two hybridspecial symbols; the hybrid special symbol 18 that has a dual functionof being a scatter symbol (in addition to being a special symbol) andthe hybrid special symbol 25 that has a triple function of being ascatter and substitute symbol (in addition to being a special symbol).

It will be appreciated that while the preferred embodiments havedescribed the group 15 as taking up all the cells 12 in each reel 11, inother preferred forms the group 15 need only take up or fill a certainpercentage of the available cells 12 in the array 10. To provide adiscernible advantage to the player the group should occupy at leastmore than 50% of the available cells 12 in the array 10 (as best shownin FIG. 10). In particularly preferred forms, the group 15 fills in atleast 60% (as best shown in FIGS. 4, 11 and 12), 80% (as best shown inFIG. 5), 90% (as best shown in FIG. 8) or all of the available cells 12in the array 10 (as best shown in FIG. 6). Also, the group 15 can beselected such that the number S of special symbols 16 is related to thenumber R of available cells 12 in the array. For example, the group canbe selected so that S=R (i.e., all available cells 12 in the array 10,as in FIG. 6), S=R−1 (as best shown in FIG. 8), S=R−2 and S=R−3 (as bestshown in FIGS. 5 and 7). Furthermore, the group 15 can be selected suchthat the number S of special symbols 16 is a minimum number. Forexample, the group 15 can be selected such that 6<S<R (as best shown inFIG. 10) or S>9 where R>15 (as best shown in FIG. 13).

In the preferred embodiments of the invention, the aim is for the group15 to be displayed so that each play of the game results in an outcomedisplaying a plurality of the same, equivalent or associated specialsymbols in a majority of available cells 12 such that the said specialsymbols 16 are aligned in winning patterns and combinations. There aremany ways to achieve this result, some of which include, but are notlimited to, the following;

-   (a) the game 8 provides reel strips heavily loaded with the special    symbols 16 in at least one of a base game and a feature game;-   (b) the game 8 comprises a trigger event that causes or triggers a    large number of (or all of) the available cells 12 to display the    group 15 of special symbols 16;-   (c) the game 8 comprises a trigger event that causes or triggers a    large number of (or all of) the game symbols 9 displayed on the    array 10 to change, transform or morph into the special symbols 16;-   (d) the game 8 comprises a feature game wherein it is guaranteed a    large number of (or all of) the available cells 12 will display the    special symbols 16 at least once during play of the feature game    each time the feature game is triggered, and-   (e) the game 8 provides a feature game wherein the probability of    triggering the appearance of a group 15 that comprises a large    number of (or all of) the available cells 12 to display the special    symbols 16 is increased in comparison the probability of the same    event occurring in the base game.

In other preferred forms, the game 8 comprises a base game and a featuregame where the feature game provides a sequence of plays of the featuregame that are typically free. In this case the feature game is activatedor triggered by a trigger event during play of the base game, and in thefeature game it is guaranteed that S=R for at least one play of thefeature game played during that sequence of plays each time the featuregame is activated or triggered. Likewise, in another preferred form, itis guaranteed that S>0.5×R for at least one play of the feature gameplayed during that sequence of plays each time the feature game isactivated or triggered.

Also, while the preferred embodiments have described that the availablecells 12 of the array 10 equal all the cells shown on the array, it willbe appreciated that in other preferred forms, a number of the cells arenot available for play during the game. For example, depending on theamount of the bet wagered by the player, he or she may only be able toaccess three of the reels 11 making only nine cells 12 being availablefor play. Only by making a further ante-bet, the player can access oneor more the remaining reels (and hence cells). In this case, only the“active” or available cells 12 will be use in determining theprobability of the group 15 appearing during play of the game.

In other preferred forms, the special symbol 16 is selected from one ofthe game symbols 9 other than acting as a substitute symbol 9 a. Forexample, the special symbol 16 can be a “top paying” game symbol (i.e.,one in which a combination of those symbols confers the highest prizevalue). Alternatively, the special symbol 16 is a new symbol, such as areveal symbol that changes, transforms or morphs into any game symbolsand at least pays winnings on the resultant symbols.

In a further preferred form, the group 15 comprises different types ofspecial symbols 16, but the special symbols in the group are associatedwith each other. This can be achieved by having special symbols compriseat least one or more of game symbols that are visually the same, have acommon element, share a common enhancing effect on the outcome of thegame, and have an additional function in said game. In one variation,the common element comprises an image associated with, or arepresentation of, said special symbols in said group. For example, animage corresponding to the image of the substitute symbol or the word“WILD” can be added to a symbol associated with the substitute symbol toindicate their association as special symbols in the same group. Thus,the group 15 can comprise substitute symbols 9 b, symbols equivalent tothe substitute symbol or any symbol associated with the substitutesymbol.

In another variation, the common element comprises an image associatedwith, or a representation of, said group. For example, the group 15 cancomprise symbols that have different images, but each have the word“SUPER” or an image like a star to indicate that they belong to the samegroup, where the “SUPER” word or star image is not present in any of thegame symbols 9.

In other embodiments, the group 15 can be a predetermined set of cells12 in the array 10. For example, the group 15 can be the at least tenadjacent cells 12 that fill the cells in the reels 11 from the left mostreel 11 a of the array 10. Alternatively, the group 15 can be the atleast ten adjacent cells 12 that fill the cells in the reels 11 from theright most reel 11 e of the array 10. In another example, the group 15can be the at least fifteen adjacent cells 12 that fill the cells in thereels 11 from the left most reel 11 a of the array 10. Alternatively,the group 15 can be the at least fifteen adjacent cells 12 that fill thecells in the reels 11 from the right most reel 11 e of the array 10.

In the preferred embodiments described above, the cells 12 in which theTriggerS symbol 18 and the TriggerSP symbol 20 appear are chosen to bepart of the group 15 of special symbols 16. However, it will beappreciated that in other embodiments the cells 12 in which TriggerSsymbol 18 and the TriggerSP symbol 20 do not form part of the group 15of special symbols 16.

In another preferred form, the individual cells 12 each represent asingle “reel” so that the 5×3 array 10 in FIG. 3 has 15 separate reelsinstead of 5 reels. In this case, the invention would function in thesame way, with the electronic game controller 4 selecting reels insteadof cells 12 for the group 15 of special symbols 16 appear on the array10.

In a further preferred form, the electronic game controller 4 determineswinning combinations of the game symbols 9 at the conclusion of the spinof the reels 11 before determining whether the appearance of the group15 on the array 10. In this embodiment, the player is given a secondchance to obtain winning combinations of game symbols for a single spinof the reels 11. This embodiment adds to the player's excitement andthus retains his or her interest in playing the game 8 on the electronicgaming machine 1.

In yet another preferred form, the electronic game controller 4 does notwait for all the reels to stop spinning before making a determination asto the appearance of the group 15 of special symbol 16. Instead, theelectronic game controller 4 initiates selection of the group 15 beforethe reels 11 stop spinning. This preferred form can heighten theplayer's anticipation while waiting for the reels 11 to stop spinning.

It will also be appreciated that the invention may be applied to eithera main or “base” game or a feature game offered on the electronic gamingmachine. Alternatively, the invention can be applied to both the basegame and a feature game. In this case, the electronic game controller 4controls the display so that during play of the base game on the arrayand in response to a trigger event, the electronic game controller 4causes a feature game (not shown) to be displayed on the array. In oneembodiment, the use of the TriggerS symbol 17, Trigger SP symbol 20and/or the group 15 of special symbols 16 can be an additional featureof the base game that is accessible upon the player can making anadditional side bet or ante-bet during play of the game 8.

The feature game may employ the same array as the base game, as well asthe same game symbols 9 that are used in the base game. However, it willbe appreciated that the array for the feature game may vary from thebase game. For example, the feature game could adopt a different formatof cells and/or use an entirely different set of game symbols, or amixture of game symbols from the base game and different game symbols.

Where the feature game adopts a reel-type format as illustrated in FIGS.3 to 13, it typically comprises a predetermined number of free plays orspins of the reels 11. That is, the reels 11 in the feature game arespun without requiring the player to make a bet, unlike the base game.The number of free spins remaining in the feature game is typicallyindicated on the screen 7 by a suitable counter (not shown). In thefeature game, predetermined winning combinations of randomly selectedgame symbols 9 result in the award of prizes to the player, usually ofan enhanced value compared to the prizes awarded in the base game.

The video display screen 7 may also include a top screen, either as aseparate display or integrated into the display screen 7, which providesjackpot information in the form of a major jackpot information box and aminor jackpot information box. The top screen ensures that the jackpotinformation is available to the player at all times during play of theelectronic gaming machine 1.

In other preferred forms, the game 8 has other features like jackpotprizes. The jackpot prize can be shared with any other games offered onthe electronic gaming machine (as in multi-game gaming machined) orgames offered on separate electronic gaming machines. Informationrelating to the jackpot prize(s) can be provided on the screen 7 or viaa top screen that is devoted to displaying jackpot information. In onepreferred form, the jackpot prize comprises a mystery jackpot. That is,none of the symbols in the game trigger the jackpot; hence thetriggering event is a “mystery”. By way of comparison, a standardjackpot is typically symbol driven in that a particular combination ofsymbols must occur in the game to trigger the standard jackpot.

Also, in a further preferred form, the player can selectively stopspinning of the reels 11 to increase player interaction. Furthermore,the player can start spinning of the reels 11 to further enhance playerinteraction.

In the preferred embodiments, the video display screen 7 is a touchscreen for use in addition to the player-actuatable buttons 6. Thisenables the player to select various features, such as responding to anymessages or requests issued on the electronic gaming machine 1 by theelectronic game controller 4. In this case, the player may control whenthe reels 11 start spinning and stop spinning in any of the games 8 bysimply touching the relevant reel 11.

It will be appreciated that while the preferred embodiments have beendescribed in relation to an industry standard electronic gaming machine,the invention can be readily applied to other types of electronic gamingmachines, including a personal computer (standing alone or connected toa communications network, LAN or WAN), mobile electronic devices (suchas handheld or portable electronic devices) and other electronic devicescapable of displaying a game. In the case of mobile electronic device,in one arrangement it may permit the player to make bets using “virtual”credits that represent a monetary value, but do not require the playerto make a monetary transaction. Instead, the invention may provide atiered access to the various features of the game so that the player canmake relatively small payments to access particular features of the gameor obtain additional benefits during game play. An alternativearrangement would require the player to purchase virtual credits ortokens via an interface on the mobile electronic device or an onlineinterface accessible by the mobile electronic device. Similarly, eitherof the above described arrangements can be applied where the inventionis implemented on a personal computer (PC) connected to the internet(wirelessly or not). In one example of the implementation, the PC wouldaccess an online casino over the internet to play the game of theinvention or the game of the invention would be part of a socialnetworking website. It is also contemplated that the player could alsomake regular payments to subscribe to continue playing the game on themobile electronic device, PC or other electronic device.

In an alternative embodiment, the electronic gaming machine alsoprovides an option for the player to play with either credits based on amonetary amount or virtual credits as discussed above. This can beimplemented by way of a selection menu prior to playing the selectedgame or by providing a suitable menu button on screen during play of theselected game.

In another aspect, the invention includes a computer program configuredto perform the invention. In this way the invention can be implementedin various ways on an electronic gaming machine. In a further aspect,the invention includes a computer system configured comprising a centralprocessing unit configured for communication with an electronic gamingmachine to perform the invention. In a yet another aspect, the inventionincludes a non-transitive carrier medium carrying computer executablecode that, when executed on a central processing unit configured forcommunication with an electronic gaming machine, causes said centralprocessing unit to perform the invention. In this case, thenon-transitive carrier medium includes an external hard drive, a memorydevice, including a memory card, smart card, a radio frequencyidentification (RFID) device, USB key, magnetic card or other electronicstorage device.

It will further be appreciated that any of the features in the preferredembodiments of the invention can be combined together and are notnecessarily applied in isolation from each other. For example, the useof the special symbols 15 and 16 can be a side or ante-bet feature of abase game can be combined with the provision of a separate feature game.

By providing a group of special symbols that fill most or all of thearray and a significantly higher hit rate or probability of occurringduring game play, players are more likely to see the array filled oralmost filled by the same symbols, thus increasing the chances of alarge win and thus retains the player's interest and encourages theplayer to continue playing the various games on the same electronicgaming machine. Furthermore, since the electronic game controllercontrols operation of the electronic gaming machine, the invention canbe readily implemented to existing gaming machines and other gamingsystems. In all these respects, the invention represents a practical andcommercially significant improvement over the prior art.

Although the invention has been described with reference to specificexamples, it will be appreciated by those skilled in the art that theinvention may be embodied in many other forms.

1. An electronic gaming machine comprising: a display for displaying agame comprising game symbols arranged into an array of predeterminedgame positions, wherein R is the number of available predetermined gamepositions for play in said game and predetermined winning combinationsof randomly selected game symbols in each game award prizes to a player,and an electronic game controller for controlling the display of saidgame symbols on said display, wherein said electronic game controllerdetermines the appearance of a group of special symbols in saidpredetermined game positions, said group affecting the outcome of saidgame and S being the number of special symbols in said group, andwherein the probability of said group appearing on said array is lessthan 1 in X, X being the average number of games played with said Rpredetermined game positions.
 2. The electronic gaming machine of claim1, wherein said game is a base game and said predetermined gamepositions are selectable for play by said player, wherein X is thetheoretical average number of games required for the appearance saidgroup to occur when R predetermined game positions are selected forplay.
 3. The electronic gaming machine of claim 1, wherein said gamecomprises a feature game and a trigger event in a base game activatessaid feature game for play, said predetermined game positions beingselectable for play by said player in said feature game, and wherein Xis the theoretical average number of games required for the appearanceof said group to occur in said feature game multiplied by theprobability of said trigger event occurring in said base game, when Rpredetermined game positions are selected for play.
 4. The electronicgaming machine of claim 1, wherein said predetermined game positions arearranged in rows and/or columns in said array.
 5. The electronic gamingmachine of claim 1, wherein said special symbols in said group areassociated with each other.
 6. The electronic gaming machine of claim 5,wherein said special symbols comprise at least one or more of gamesymbols that are visually the same, have a common element, share acommon enhancing effect on the outcome of the game, and have anadditional function in said game.
 7. The electronic gaming machine ofclaim 6, wherein said common element comprises an image associated with,or a representation of, said special symbols in said group.
 8. Theelectronic gaming machine of claim 6, wherein said common elementcomprises an image associated with, or a representation of, said group.9. The electronic gaming machine of claim 6, wherein said additionalfunction is to act as at least one of a scatter symbol, trigger symbol,substitute symbol and jackpot symbol.
 10. The electronic gaming machineof claim 1, wherein at least two special symbols of said group form partof at least one of said predetermined winning combinations of gamesymbols.
 11. The electronic gaming machine of claim 1, wherein at leasttwo special symbols of said group form part of at least two of saidpredetermined winning combinations of game symbols.
 12. The electronicgaming machine of claim 1, wherein X is between 25 and 10,000,inclusive.
 13. The electronic gaming machine of claim 1, wherein S is atleast one of: (a) S=R; (b) 6<S<R; (c) 9<S<R; (d) 12<S<R; (e) S=R−1; (f)S=R−2; (g) S=R−3; (h) S>9 when R>15; (i) S>0.5×R; (j) S≧0.6×R; (k)S≧0.7×R; (l) S≧0.8×R, and (m) S≧0.9×R.
 14. The electronic gaming machineof claim 1, wherein said group comprises at least ten to fifteenpredetermined game positions adjacent each other starting from theleftmost side of said array.
 15. The electronic gaming machine of claim1, wherein said group occupies at least ten to fifteen predeterminedgame positions adjacent each other starting from the rightmost side ofsaid array.
 16. The electronic gaming machine of claim 1, wherein saidgroup occupies at least the predetermined games positions to the left ofa centre line of said array.
 17. The electronic gaming machine of claim1, wherein said group occupies at least the predetermined gamespositions to the right of a centre line of said array.
 18. Theelectronic gaming machine of claim 1, wherein said game comprises a basegame and a feature game, said feature game being triggered by a triggerevent in said base game and comprising a sequence of plays of saidfeature game, wherein at least one of S>0.5×R and S=R is guaranteed forat least one of said plays that is played during said sequence for eachfeature game triggered by said trigger event.
 19. The electronic gamingmachine of claim 1, wherein said special symbol comprises at least oneof: (a) a top paying game symbol in which a combination of said toppaying game symbols confers the highest prize value; (b) a substitutesymbols, a symbol equivalent to said substitute symbol or any symbolassociated with said substitute symbol, and (c) a reveal symbol thatchanges, transforms or morphs into any game symbols and at least payswinnings on the resultant symbols.
 20. The electronic gaming machine ofclaim 1, wherein said game comprises a plurality of additional arrays ofgame symbols arranged in predetermined game positions and the number ofpredetermined game positions R is limited to the available predeterminedgame positions of said array and excludes the predetermined gamepositions of said additional arrays.
 21. A gaming method for playing anelectronic gaming machine comprising a display and an electronic gamecontroller, the method comprising the steps of: controllably displayinggame symbols on said display for playing a game, wherein said gamesymbols are arranged into an array of predetermined game positions,wherein R is the number of available predetermined game positions forplay in said game and predetermined winning combinations of randomlyselected game symbols award prizes to a player; controllably determiningthe appearance of a group of special symbols on said display, S beingthe number of special symbols in said group, so that the probability ofsaid group appearing on said array is less than 1 in X, X being theaverage number of games played with said R predetermined game positions,and determining any changes to the outcome of said game based on theappearance of said group.
 22. The gaming method of claim 21, whereinsaid game is a base game and said method further comprises the step ofselecting predetermined game positions for play, wherein X is thetheoretical average number of games required for the appearance saidgroup to occur when R predetermined game positions are selected forplay.
 23. The gaming method of claim 21, wherein said game comprises afeature game and said method further comprises the steps of activatingsaid feature game in response to a trigger event in a base game andselecting said predetermined game positions for play in said featuregame, wherein X is the theoretical average number of games required forthe appearance of said group to occur in said feature game multiplied bythe probability of said trigger event occurring in said base game, whenR predetermined game positions are selected for play.
 24. The gamingmethod of claim 21, wherein said method further comprises arranging saidpredetermined game positions in rows and/or columns in said array. 25.The gaming method of claim 21, wherein said method further comprisesassociating said special symbols in said group with each other.
 26. Thegaming method of claim 25, wherein said associating step comprisesproviding said special symbols that comprise at least one or more ofgame symbols that are visually the same, have a common element, share acommon enhancing effect on the outcome of the game, and have anadditional function in said game.
 27. The gaming method of claim 26,wherein said associating step comprises associating an image associatedwith, or providing a representation of, said special symbols in saidgroup.
 28. The gaming method of claim 26, wherein said associating stepcomprises associating an image associated with, or providing arepresentation of, said group.
 29. The gaming method of claim 26,wherein said associating step comprises providing said additionalfunction that acts as at least one of a scatter symbol, trigger symbol,substitute symbol and jackpot symbol.
 30. The gaming method of claim 21,wherein said group determining step comprises causing at least twospecial symbols of said group to form part of at least one of saidpredetermined winning combinations of game symbols.
 31. The gamingmethod of claim 21, wherein said group determining step comprisescausing at least two special symbols of said group to form part of atleast two of said predetermined winning combinations of game symbols.32. The gaming method of claim 21, further comprising the step of makingX between 25 and 10,000, inclusive.
 33. The gaming method of claim 21,wherein said group determining step comprises causing the appearance ofsaid group such that S is at least one of: (a) S=R; (b) 6<S<R; (c)9<S<R; (d) 12<S<R; (e) S=R−1; (f) S=R−2; (g) S=R−3; (h) S>9 when R>15;(i) S>0.5×R; (j) S≧0.6×R; (k) S≧0.7×R; (l) S≧0.8×R, and (m) S≧0.9×R. 34.The gaming method of claim 21, wherein said group determining stepfurther comprises causing special symbols to appear in at least ten tofifteen predetermined game positions adjacent each other starting fromthe leftmost side of said array.
 35. The gaming method of claim 21,wherein said group determining step further comprises causing specialsymbols to appear in at least ten to fifteen predetermined gamepositions adjacent each other starting from the rightmost side of saidarray.
 36. The gaming method of claim 21, wherein said group determiningstep further comprises causing special symbols to appear in at least thepredetermined games positions to the left of a centre line of saidarray.
 37. The gaming method of claim 21, wherein said group determiningstep further comprises causing special symbols to appear in at least thepredetermined games positions to the right of a centre line of saidarray.
 38. The gaming method of claim 21, wherein said game comprises abase game and a feature game, said method further comprising triggeringsaid feature game in response to a trigger event in said base game,providing a sequence of plays of said feature game and guaranteeing atleast one of S=R and S>0.5×R for at least one of said plays that isplayed during said sequence for each feature game triggered by saidtrigger event.
 39. The gaming method of claim 21, wherein said methodfurther comprises providing a plurality of additional arrays of gamesymbols arranged in predetermined game positions on said display andrestricting R to the available predetermined game positions of saidarray and excluding the predetermined game positions of said additionalarrays.
 40. A computer system comprising a central processing unitconfigured for communication with an electronic gaming machine, whereinsaid computer system is configured to perform the method of claim 21.41. A computer program configured to perform the method of claim
 21. 42.A non-transitive carrier medium carrying computer executable code that,when executed on a central processing unit configured for communicationwith an electronic gaming machine, causes said central processing unitto perform the method of claim 21.